TOPIC: Images missing from Emailed Invoice

I've have several logos within my invoice template and they do not appear within the actual email sent. I've checked the source code of the sent email and the references to the logos are using relative addressing (relative to the domain) instead of absolute. As such the reference for example would look like:

Upon further inspection, it appears that the absolute uri from the image is being stripped out when I select the pdf template to email the invoice. So it is being stripped out before the email leaves suitecrm. Is this a setting in the htmlPurifier doing this. Where is the source code for this so I can take a look.